Speedometer



July 31, lsza 1,679,203 G. w. BLACKBURN SPEEDOMETER July 31,A 1928. 1,679,203

, G. w. BLACKBURN n sPEDoMEfrER Filed April 9, 1924 2 sheets-sheet 2 @71.31F 16E/ win32 "H 'l/l. iff-W l---m'A HIL,w M i;

mlllll 42W* www Patented July 3l, 1928.

UNITED@ STATES PATENT ori-ice GUY W. BLACKBURN, or ELGIN, ILLINOIS.

sPEEDoiviirrna.

application nica April 9, i924. serial No. 705,235.

speed in `terms of revolutions per minute,

miles per hour or any lother unit.

One object of my invention is to provide a mechanical speed indicator which will be compact, noiseless and'accurate and which will maintain this accuracy throughout the entire speed range, and which. will alwa s return to the zero when the machinery, t ie speed of which is being indicated, aceases to operate. Another object is to provide a niechanical speed indicator of such size and shape as will bewell adapted for use in connection with the instrument board of an automotive vehicle Another object is to provide in connection with a speedl indicator separate means for giving a positive signal in the event that a certain predetermined speed has been exceeded and to provide a switch which can be used for any desirable purpose, as for indicating or stopping the vehicle when a certain speed has been exceeded. Other objects will appear from time to time in the specification.

My invention is illustrated. more or less diagrammatically in the accompanying drawings, wherein- Figure 1 is a front elevation;

Figure 2 is a topplan view;

`Figure 3 is a section alongline---- of Figures l and. 2; e

Figure 4 is a top plan View of the mechanism in part section as itV appears removed from the housing, showing the parts for -il'-.

lustration in the position that they wouldy assume at thirty miles an hour on an auto.- motive vehicle; Y'

Figure 5 is an inverted plany viewof the partsshown in Figure 4;

Figure 6 is a horizontal section through the indicating drum; f v

Figure 7 is a section along line 7-7 of Figure 3; y

Figure 8 is a section .along line 8.-8 of Figure 4; v

Figure 9 is a section with along line 9 9 of `Figure 7;

Figure 10 is a detail of the speed limit switch.

Like parts are indicated by like characters throughout.

parts omitted A is a cylindrical metallic housin a clo's'edend A1 and open at the other end. A2 is a flared flange surrounding the open end and containing a packing ring A3 of rubber or other suitable material. A4A is a cover ring slidable on the flange A2 and adapted tovhold a cover A5 ot' glass or othersuitablematerial in the open mouth of the i ha lS g housing, against the packing ring A3. isa collar associated with the cover ring A4, outwardly flared and adapted to rest against the face of an instrumentv boardA7 and to close and protect the opening through which the apparatus is inserted insuchboard. As

is a flexible shaft or other suitable form of power transmitting means by which power is transmitted from the machinery, the speed of which is indicated, to the apparatus through the usual type of worm gear not here shown, enclosed in the housing A9.

Bv is a support-ing frame held by cap screws B1 on the closed end ofthe housing A1. This supporting frame carries an indi-V cator shaft B2 driven bythe worm gear inl housing A9 and also .carries a revolution counter B3, the details of which form no part of my invention and are not here illustrated. This revolution counter .preferably Y takes the form of season and trip indicator wheelsB4 B5 visible through the face ofthe cover A5, and are driven by any suitable means, not here shown, in response to lthe rotation of the shaft B2. B6 is a speed indicating drum closed at the top and open at thebottom. It is mounted in and rotates with. a spindle B7.

The lower pointed end 0 having p l i of the spindle rests onA a fixed pin B8 projecting upwardly from the frame C. The upper pointed end is guided in the adjusting screw B9 in the bracket B10, mounted on the frame C. An ear B11 projects upwardly from the top of he drum B6, adapted to engage the downwardly bent end B13 of a vstop armv B14, rotatably adjustable on the bracket B1o to limit the excursion ofthe speedv indicatingdrum when returning to zero.

C is a bracket fixed on the frame B and associated with lthe pin B8, projecting forwardly toward the front end of the housing. This bracket carries a pivot pin C1, upon which. is rotatably mounted the lever C2, which. lever comprises a fulcrum Cia closed loop C41 surrounding but out of contact with a part vof the bracket C, a pin B8 and operating end C5. C is a curvedv rack concentric with the center of rotation ot' the lever, in mesh with a pinion C7 on a sleeve C8, which sleeve is rotatable on the pin B2 and carries a driving arm C connected by means of a coiled spring C10 to the pin B2 so that rotation ot the lever C2 rotates t-he pinion C2, the arm C9 and through the coiled spring C10 the pin l5? and drum BG. C11 is an oil channel mounted on the bracket C and containing oilinto which the lower edge of the drum BG dips. This oil is relatively thick so as todamp or check the rotation of the drum B6 and have a dash pot effect upon it. C12 is a coiled spring interposed between the pin C1 and the lever C2 and tending at all times to yieldingly thrust the lever toward the left as viewed in Figures 4 and 7,' and with it the drum in the Zero speed position. Rotation ot the lever in a clock-wise direction against the spring causes it to carry with it the drum B6 and indicate speed.

lillounted on the shaft B2 is a tachometer screw EL This screw is cylindrical and has a tine thread thereon. rThis thread is interrupted by two diametrieally opposed slots DL El wound spirally about the cylinder in a direction opposite to the lead oi' the threadl and increasing in width from the left or Zero end of the cylinder to the right so that the effective length of uninterrupted thread decreases toward the right or high speed end of the screw. E2 is a sharp edged roller having one surface toward the left or lowv speed end perpendicular to the axis of rotation and a conical suriace toward the right or high speed end ot' the screw. This roller is rotatably and slidably :mounted on the thin light bearing rod D3, and it is provided with collars Dlv adapted to be engaged by a fork D2 on a universal joint pin D6. This pin engages a radial slot D2 in the working end C5 of the lever C22 this slot being of sub* stantially the same width as the diameter ot' the. collar D8 on the pin. The upper endY of the pin D is provided with two opposed spherical surfaced collars D2 D10 one engaging the upper and the other the lower side ot' a pertorate flange D, inwardly projecting 'from the extension D12 on the 'end of the. lever C2. This furnishes a connection between the pin D and the lever C2 so that as the roller travels laterally ina direction parallel with the axis ot rotation of the screw itchanges its distance from the `center of rotation of the lever, and it is tree to swing, but it is held against angular move-4 ment with respect to the lever. The result of this is that movement ot the roller D2im` parts :1i-.positive angular Vmovement to the lever C2.

The pin D3 is mounted at either end in spring brackets E. El on the adjustable can riage E2. yThis carriage is mounted on a base l being held in position thereonby the screws E3 engaging slots E4 in the carriage E2 so that the carriage springs, pin and roller may be Amoved radially toward and from the screw to adjust the engagement oil the roller with the screw. These springs E El project outwardly and are engaged by a main spring E5 which is rigidly mounted on the frame B. There are three adjusting screws tor this main spring, a central screw E, and end screws E7 E8 all associated with the lug E9 on the member' B so that the up and down movement of the entire spring asseinbly may be noiselessly adjusted. The two end `screws E7 ES are associated with adjusting cams E10 whereby the downward pressure oi the two springs E El may be separately adjusted tou control the spring` pressure ci the roller toward the screw and to insure that the roller will engage the screw but be free to slip over the screw if that becomes necessary as later pointed out.V

0n t-he end of the lever C2 is a stop pin F. This stop pinA E is adapted to be engaged when the speed reaches a. predetermined point byv a spring finger El downwardly extending Afrom a contact arm F2. This contact arm is pivoted on the adjustable speed limit lever E3 and carries a contact plug F* in opposition to a contact plug F5 tixed on the leverll. This contact member F2 is insulated trom the balance of the lever E, hasa spring arm E? engaging a spring contact plate F77 the contact being normally heldopen by the end E15 of the spring arm FG. j The lever F3 is pivoted on a plug F8 and is associated with a segment gear F2 in mesh with an adjusting pinion F10 associated with a thumb screw F11 having a pointer F12 working across the face of the dial F23. As shown in the drawing the pointer isset for thirty miles per hour. l/Vhen the speed reaches that point the pin E engages the spring lll to bring the two contact members E* F5 together and closes an electrical circuit. This circuit may ring a bell, operate an indicator ot some other kind or may be connected up to any suitable mechanism tor stopping the enginejV as 'for instance by disconnecting the ignitioi'i circuit. By inanipin lating the'pointer the speed at which this contact takes place may be set 'for any desiredpoint. y s l It will be evident that while I have shown in my drawings "an operative device5 still many changes might be made in the size, shape and arrangement ot' part-s without departing materially from the spirit ot my invention. l wishr therefore7 that my showing be taken as in a large sense diagrammatic. The spiral slot is. provided so as to insure that as the vehicle slowsdown there will be little if any danger of the carrier being caught on the thread and locked into a position where it would indicate a speed with the vehicle at rest Experience showed with earlier types where the groove was parallel with the axis and not spiralled about, it that this would sometimes happen. and that the addition oi' the spiral slot would` prevent it.

The use and operation. of my invention are as follows:

The mutilated screwis connected to the road wheel or vehicle or to a n ioving part in any desired way as for instance, by means 0f f a flexible shaft noty here shown. It rotates at a speed bearing a direct relation tothe moving part, the speed of which is to be indicated. As it rotates it pulls the sharp edged roller away from the zero end of the screw toward the high speed end and as the roller travels longitudinally along the screw, it carries with it the lever, and the flexible conection between the lever and roll and their support permits the movement of the parts with av minimum of friction and lost motion. As thev lever is rotated, the yielding adjustable spring isv compressed and tends always to resist movement of the roll and lever and'tends to return them to the zero position. 1

As the roll travels. up the thread, the thread eectivelydecreases because of the increased width of the sloty or multilation of the thread. The result o this is that as the roll travels up it finally reaches a pointl where the backward movement iunder the urge of the lever and spring during the time when the roll is outof contact with the thread is equal to the upward movement lduring the time when the roll isv in contact and since it isconnected to the lever by a spring which tends to damp out or absorb the vibrationl of the lever, the drum will remain at rest, this being aided bythe damping effect of the viscous material in which the lower edge of the drum is immersed.

Thus, while the lever has aslight movement,

as the roll moves back and forth along the thread, the drum will 'give' a positive and fixed indication.

There are a number of associated adjusting or Calibrating parts. If" the operator changes the tension on the spring resisting the rotation of the lever, he will cause the lever to go back a longer lor a shorter distance during the time when the roll is out of contact with the thread. Hev also can move the roll towardA and from the thread so as to change slightly thel point of engagement and thus the apparatus can be accurately .calibrated to give proper vspeed indi cations. Y

The sharp edge on the roller-engaging with the sharp screw threads andA owing'` to the lightweight of the roller itself, permits the operation of the deviceV to' be exceedingly quiet and insures ythat if Vthe sharp edge of the roller should happen to strike theapcxj` of the thread, it will slide off 'onto'the threadv itself and a correct indication be given. The

spring support for the roller makes this with the thread and giving a speed indica tion, but when the partsA areA at rest by winding the slot around the axis of rotation, this is impossible because there is always ample time for the roller to drop back to the zero position as the screw slows down. r

Thev electric circuit closing means are provided so that the operator can set the -adjustable side of the switch at any desired speed and then whenv the lever is raised up toV that speed indication, the pin on the lever will engage a switch arm and close.` an electrical circuit. This might ringa'bell or disconnect the motor of the vehicle with which the speedometer is used from the ignition, or anything thaty can be done-by arelatively small electric current such asfcanlbe-controlled by a switch of this type.` Y i Iclaim f l. Inaspeed indicator,a rotatablymounted visual indicating drum', mechanical means for rotating it through a predetermined angle' in response tol speed. variations l and yielding means for resisting the rotation of the drum, said means comprising arecefpedge of the drum only isimmersed'.,

2. Inaspeed indicator,a rotatably mounted visual indicating drum, means for rotating it through a. predetermined angle in response to speed variationsv and f yielding means for resisting the rotationl of the drum comprising a receptacle surrounding a por` tion of the drum only and a viscousliquid contained therein in which the drum'is partially immersed.

3. The combination with va rotating visual indicating drum for speed indicators and the like of an annular liquid containing ring in which the lower i immersed.

4'. The combination with a rotating visual indicating drum for speed indicators and the like of an annular liquid containing ring in which the lower edge oi' the drum only is immersed, and a closure for the ring adapted to form a 'liquid reservoir and hold the' liquid therein independent of the position thereof. v

5. A speed indicator comprising ay threadedge'of the drum only is' Si) I tacle containing' an oil bath in which-the his ist

ed cylinder, a carrier in engagement there-V with and adapted to be moved therealong" the thread, increasing in width in the direction of travel of the carrier, the axis of the slot being substantially inclined to both sides of the cylinder.

6. In a speed indicator, a threaded cylinder having a slot in the periphery thereof interrupting the thread and increasing in width from one end of the cylinder to the other, a member mounted for movement parallel with the axis of the cylinder and adapted to engage the thread, the slot being wound about the cylinder beth sides of the slot being inclined to the airis of the cylinder.

7. In a speed indicator, a threaded cylinder having a slot in the periphery thereof interrupting the thread and increasing in width from one end of the cylinder to the other, a member mounted for movement parallel with theaxis of the cylinder and adapted to engage the thread, the slot being wound about the cylinder in a direction opposite to the thread both sides et the slot being inclined to the aXis of the cylinder.

8. In a speed indicator, a threaded cylinder, a roller having a single sharp edge adapted to engage the thread', a guide rod therefor parallel with the cylinder and upon which the roller is slidably and rotatably mounted.

9. In a speed indicator, a threaded cylinder, a roller having a single sharp edge adapted to engage the thread, a guide rod therefor parallel with the cylinder and upon which the roller is slidably and rotatably mounted, and yieldingr means for support ing the guide rod;

10. In a. speedindicator, a threaded cylin der, a roller having a single sharp edge adapted to engage the thread,a guide rod therefor parallel with the cylinder and upon which the roller is slidably and rotatably mounted, yielding means for supporting the guide rod` and means for adjusting the rod independently at each end toward and from the roller.

1l. In a speed indicator, a threaded cylinder, a roller having a single sharp edge adapted to engage the thread. a guide rod ltherefor parallel with the cylinder and upon which the roller is slidably and rotatably mounted. yielding means for supporting the guide rod, and means for independently adjusting the tension at each end to move the roller toward and from the roller.

l2. In a speed indicator, a threaded cylinder, a roller havingl a single sharpedge adapted to engage the thread, a guide rod therefor parallel with the cylinder and upon which the roller is slidably and rotatably mounted, a carriage for the guide rod and vmeans yformoving it radially toward and from the cylinder,- and yielding means for supporting the 'guide rod on the carriage.

le. @In a speedindicator, a threaded cylinder, a roller having a single sharp edge adapted to engage the thread, a guide rod therefor' parallel with the cylinder and upon which the roller is slidably and rotatably mounted, a carriage for the guide rod and means for moving it radially toward and from the cylinder, yielding means for supporting the guide rod on the carriage, and means for independently adjusting the ten-A sion of the yielding supporting means at either end of the guide rod.

l5. In a speed indicator, a lead screw, a roll engaging the thread thereof and adapted to be moved thereby to give speed indication and a yielding support for the roll, the roll having a single sharp edge adapted invariably to penetrate between the threads,

1G. A speed indicator comprising a mutilated screw, the effective length of the threads of which decrease from the zero end, a sharp edged roll in engagement with and mounted for movement therealong, and a yielding adjustable support therefor, a. speed indicating lever and aiiexible connection beH tween it and the roll whereby the lever be rotated by movement ofthe roll along the thread, yielding means resisting such rotation and tending toA return the lever and roll toward the zero end of the screw, an independently supported rotatable indicating drum, a yielding driving connection between it and the lever and means associated with the drum for damping its vibration.

i7. A speed indicator comprising a mutilated screw, the effective length of the threads of which decrease from the zero end, a sharp edged roll in engagement with end mounted for movement therealong, and a yielding adjustable support therefor, a

'speed indicating lever and flexible connec-V tion between it and the roll whereby the lever may be rotated by movement of the roll along the thread, yielding means resisting such rotationand tending to return the lever and roll toward the zero end of the screw,` an independently supported rotatable indicating drum, a yielding driving eonnection between it and the lever.

18. A speed indicator comprising a mutilated screw, al sharp edged roll in engagement therewith, a speed indicating lever engaging and driven by movement of the roll lll)` and an indicating drum, a drive connection between it and the lever, an independent supporting means for the screw, roll, lever and drum being each independently supported. 19. A speed indicator comprising a mutilated screw, the effective length of the threads thereof decreasing from one end of the screw to the other, a single guide rod positioned adjacent the screw and a single roller longitudinally movable along said guide rod and in mesh with said screw.

20. A speed indicator comprising a multilated screw, the effective length of the threads thereof decreasing from one end of the screw to the other, a single guide rod positioned yadjacent the screw and a single rollcr Y longitudinally movable along said guide rod and in mesh with said screw, said' guide rod being yieldably mounted.

21. A speed indicator comprising a mutilated screw, the effective length of the threads thereof decreasing from one end of the screw to the other, a single guide rod positioned adjacent the screw and a single roller longitudinally movable along said guide rod and in mesh with said screw, said guide rod being yieldably mounted and be- ,ingv adjustable toward and from the screw. l

' 22. The combination of a Screw and a follower adapted to engage 1t of means for guiding the follower along the screw, a lever Y mounted for rotation about an axis removed from the screw, a pin loosely swung in the lever at one end engaging the follower at the other end and means on the lever adapted to loosely engage the pin to transmit motion from the follower to the lever.

23. The combination of a screw and a follower adapted to engage it of means for guiding the follower along the screw, a lever mounted for rotatlon about an axis removed c from the screw, a pin loosely swung in the lever at one end engaging the follower at l the other end and means on the lever adapted to loosely engage the pin to transmit mo- `tion from the follower to the lever, the follower comprising a grooved sleeve and a sharp edged comb, the edge of which engages` guiding the follower along the screw, a lever mounted for rotation about an axis removed from the screw, a pin-loosely swung in the lever at one end engaging the follower at the other end-and means on the lever adapted to loosely engage the pin to transmitmotion from the follower to the lever, `the means for guiding the follower being adjustable toward and from the screw independent ofthe laction between the follower and the lever.

25. The combination of a screw and a follower adapted to engage .1t of means for guiding the follower along -thescrew, alever mounted for rotation about an axis removed from the screw, a pin loosely swung in the lever at one end engaging the follower at the other end and means on the lever adapted to loosely engage the pin to transmit motion from thefollower to the lever, the follower comprising a grooved sleeve and a sharp edged comb, the edge of which engages the pin, the pin being grooved to loosely engage the groove, the means forv guiding the fol#k lower being adjustable toward and from the screw independent of the action between` the follower and the lever.

Signed at Chicago county of Cook and State of Illinois, this 8th day of April, 1924. c

GUY W. BLACKBURN. 

